If you do not have an Android device or you want to test your app to a specific device/configuration, you can create an Emulator using the Android Virtual Device (AVD) Manager.
To open the AVD Manager:
- In Eclipse: select Window > Android Virtual Device Manager or click the AVD Manager icon in the toolbar.
- In Android Studio, select Tools > Android > AVD Manager or click the AVD Manager icon in the toolbar.
- If you have other IDEs or you're not using one: Navigate to <sdk-directory>/tools and execute android avd.
To create an Android Emulator:
- Open the AVD Manager
- Click the Create button.
- Fill up the name, and select the device, target, CPU/ABI, and skin. You can also add hardware functionalities, like keyboard, camera and SD card.
- Click the OK button to create the emulator
Alternatively, you can use Genymotion Emulator. Genymotion is a faster Android emulator. The free version is more than enough for an Android developer. I am using Genymotion now most of the time.